Development of capacitive sensor for measuring soil water content

Alan K Rêgo Segundo,José H Martins,Rrubens A De Oliveira,Paulo M De B Monteiro,Delly Oliveira Filho

doi:10.1590/s0100-69162011000200006

Alan K Rêgo Segundo, José H Martins + Show 3 more

Open Access

https://doi.org/10.1590/s0100-69162011000200006

Copy DOI

Abstract

The irrigation management based on the monitoring of the soil water content allows for the minimization of the amount of water applied, making its use more efficient. Taking into account these aspects, in this work, a sensor for measuring the soil water content was developed to allow real time automation of irrigation systems. This way, problems affecting crop yielding such as irregularities in the time to turn on or turn off the pump, and excess or deficit of water can be solved. To develop the sensors were used stainless steel rods, resin, and insulating varnish. The sensors measuring circuit was based on a microcontroller, which gives its output signal in the digital format. The sensors were calibrated using soil of the type “Quartzarenic Neosoil”. A third order polynomial model was fitted to the experimental data between the values of water content corresponding to the field capacity and the wilting point to correlate the soil water content obtained by the oven standard method with those measured by the electronic circuit, with a coefficient of determination of 93.17%, and an accuracy in the measures of ±0.010 kg kg-1. Based on the results, it was concluded that the sensor and its implemented measuring circuit can be used in the automation process of irrigation systems.

Highlights

The determination of the necessary water quantity for irrigation is one of the main parameters for the correct planning, dimensioning and management of any irrigation system, as well as for the evaluation of availability of hydric resources
When the quantity of necessary water is overestimated, as a consequence there are over dimensioned irrigation systems, increasing the cost of irrigation per unit of area (MANTOVANI et al, 2007)
On the other hand, when the quantity of the necessary water is underestimated, there is the sub-dimensioning of the irrigation system and, as a consequence, low yield or more frequently the incapacity of the system to irrigate the whole area of the project, that is, reduction of the area to be irrigated (BERNARDO et al, 2006)

Summary

Introduction

The determination of the necessary water quantity for irrigation is one of the main parameters for the correct planning, dimensioning and management of any irrigation system, as well as for the evaluation of availability of hydric resources. There are recommendations of fixed irrigation frequencies for each culture. It can be practical in a sense of programming the operations, this method has deficits and, or water excess, once that the climatic conditions vary during the year. There is the need to use field methods that determine, directly or indirectly, the hydric availability of the soil for the cultures, according to the prevailing environmental conditions during the development of the plants (QUEIROZ et al, 2005)

Methods

Results

Conclusion